Audi e-tron Concept: An R8 Goes Electric

09.24.09 | No Comments

Audi has made it clear that they won’t be pursuing production electric vehicles in the near future, but that didn’t stop them from building a mouth-watering EV concept. Dubbed the e-tron and based on the company’s R8 supercar, this concept has got looks to spare and more torque than you can shake a stick at.

One of Audi’s most famous features is their Quattro all-wheel drive. The e-tron retains the spirit of other Audi models, but accomplishes it’s all-wheel drive in an entirely different way. Rather than having mechanical transfer cases to power all the wheels, the e-tron simply has an electric motor for each wheel. And those electric motors are incredibly powerful. The total horsepower rating for the e-tron is 313, which seems paltry for a supercar, but those electric motors put out a combined 3,319 lb-ft of torque.

No, that is not a typo; over 3,000 torques. Acceleration from 0-to-62 mph (100 km/h) takes 4.8 seconds, which is a bit slow for a supercar (the e-tron is very heavy, more on that in a bit), but the car’s rolling acceleration is phenomenal. The 60-to-120 km/h (37-to-75 mph) acceleration takes only 4.1 seconds, so passing cars on the highway would be a breeze. However, that torque rating is a bit misleading. If all of that power were to be applied to the wheels when accelerating from a stand-still, then the car’s tires would just spin and spin until they were four puddles of rubbery goo. For comparison, a muscle car like the 2010 Chevrolet Camaro SS has 420 lb-ft of torque, and it doesn’t take much goading to spin the rear tires for a long time. Now imagine a burnout with about 8 times as much torque. You’d go through a set of tires every 100 yards.

Now, onto the weight. The e-tron weighs in at a hefty 3,527 pounds. That is about 50 pounds lighter than the V10-powered R8 5.2 FSI, but that model has 525 horsepower and much quicker acceleration times off the line (3.8 seconds from 0-to-62 mph). Despite the removal of that big V10 engine, the e-tron gained a lot of weight from its lithium-ion battery pack, which alone weighs 1,036 pounds and provides 42.4 kWh of usable electricity. The batter pack is mounted just ahead of the rear axle to maintain a desirable front-to-back weight ratio and features a liquid cooling system. All told, the e-tron has a range of 154 miles, but one would expect that number to dip considerably if you really put the pedal to the floor.

Supercars are normally known for their very aerodynamics-centric styling, but an electric supercar like the e-tron has to take that philosophy to a whole new level. The aerodynamics of internal combustion-powered supercars have two main factors (and this is simplifying greatly): air resistance and lift. You need a car that is sleek enough to cut through the air and attain speeds of 150+ mph, but you also need enough downforce to insure that the air passing under the car doesn’t cause lift, which would essentially cause the car to take off (compare the R8′s profile to an airplane’s wing and you’ll notice some definite similarities). The e-tron throws another variable into the mix: rolling resistance.

In order to maximize the range of an electric vehicle, you want the motors to do as little work as possible to attain and maintain driving speeds. By reducing rolling resistance (either through body aerodynamics, tires, or a combination of multiple factors), you decrease the amount of energy required to accelerate a car. This dovetails nicely with the idea of air resistance addressed above, but it is at odds with downforce. The most common method of creating downforce, the rear spoiler, uses an angled wing to take air that is flowing straight and have it push the car down and towards the rear. That’s great when you are going 150 mph and need traction from the rear tires, but not so great when you’re going 30 mph on a local road.

The Audi e-tron, while certainly worthy of discussion as an engineering exercise, is essentially useless in any other capacity. If you want a supercar, then you’re looking for speed, not energy efficiency; and the two are not very compatible. The problem is that truly exciting electric cars will cost upwards of $100,000, so supercar owners are the only ones who can really afford them. Production Audi models are set to focus more on clean diesel models and more efficient gasoline engines in the coming years, and that seems like a safe bet for the German automaker, as electric models are still years away from being cost-competitive in the market. That said, it’d still be a blast to take the e-tron out on a track for a day of eco-friendly supercar mayhem.